I've updated the release notes now. In order to conveniently convert to/from sRGB we need some API functions, for which I added a patch.

I talked to @Brecht Van Lommel (brecht) and it seems that this is intentional. I think we should mention this in the release notes of whenever we introduced this (with an example of how to convert the values from one to the other?). I couldn't find it in any of the 3.x release notes so far.

This was an intentional design choice. For attributes I wanted to have all color values in the same linear color space in the API and UI, regardless if they are stored as byte or float. That way the values match in color pickers, spreadsheet, shader nodes, geometry nodes.

Setting status to confirmed, but not setting as a bug yet. Waiting for Hans to confirm it.

Why BF Blender 2.90?

The report should contain exact steps to redo the bug (script, blend file etc).

See feedback about switching last_line_inserted to an integer.

Changes based on review feedback:

Not sure if there is still progress?
In any case, I will step back from reviewing, thx anyways.

Indeed the warnings are rather annoying. But I think the real bug is that since 3.0 all the Node Editors show the "Group" tab. I don't think this option should be there. So there is no way to create the new sockets anyways. (what is the point of creating them even?)

According to @Lukas Toenne (lukastoenne) in T90233:
"The warning current value '-1' matches no enum is because when loading the file the script for defining the custom tree hasn't run yet, but the node editor still has the tree loaded. Nothing to worry about."

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import bpy

Yes this has been fixed, closing.

Bug confirmed in Blender 3.01 hash dc2d18018171

Thanks for the report. Marking this as known issue since it depends on the old particle settings which is end of life.